PROJECT SUMMARY/ABSTRACT Technological advances in the neonatal intensive care unit (NICU) allow for treatments to be implemented and continued for days, weeks, or even months depending on an infant's gestation and underlying condition. During this time, the infant may experience pain and other symptoms that are difficult for healthcare providers to assess and manage, and also for parents to comprehend, which may cause them emotional distress. Currently there is a significant gap in our understanding of the symptom experience of critically ill infants at high risk of dying in the NICU compared to other pediatric and adult populations. Closing these knowledge gaps is critical to improving evidence-based care for these infants and their families. The long-term goal is to improve the symptom assessment and thereby the care that critically ill infants and families receive in the NICU. The objective of this prospective, longitudinal study is to characterize infant symptom burden among 100 infants in the NICU from multiple sources and identify associations between parents' perceptions of the infant's symptom experience and their decision-making, coping, and distress. The central hypothesis is that proper assessment and management of infant symptoms and suffering will enhance parent decision-making, as well as reduce infant suffering and parent distress. The rationale is that identifying symptoms that are most distressing for infants, parents, and clinicians will inform the design and evaluation of future interventions to improve care. The study objective will be obtained by pursuing 3 specific aims: 1) to prospectively characterize the symptom experience of critically ill infants at high risk of dying in the NICU from multiple sources (i.e. parents, nurses, medical chart review, and behavioral observation) from admission until discharge/death (or a maximum of 3 months); 2) to identify links between parents' perceptions of infant symptom burden, suffering, and quality of life and the effects on treatment decision-making and goals of care over time; and 3) to identify links between parents' perceptions of infant symptom burden, suffering, and quality of life and parent coping and distress over time. This approach is innovative because it is the first prospective study, to evaluate the symptom experience of critically ill infants in the NICU and to explore how perceptions of their experience impact parent decision- making, coping, and distress. This research is significant becauseit will inform the design of novel prospective investigations and intervention development aimed at improving symptom assessment and outcomes among infants and their families in the NICU.